Political bias in the interpretation of neuroscience

Slate has an interesting article arguing that there is a pervasive liberal bias in the interpretation of studies on political beliefs that casts right-wing voters in a bad light.

You’ll have to forgive the spectacularly wrong-headed first paragraph (summary: this week the Obama campaign has been described as panicking, so why have neuroscience studies suggested liberal voters are less fearful?) but it does make an interesting and important point.

The piece riffs on a recent study published in Science that reported that conservatives show greater skin conductance and higher blink rates to threatening images than liberals, indicating higher levels of arousal.

This was widely interpreted as suggesting conservatives are more fearful than liberals. Although the study didn’t ask about fear directly, both blinking and sweating have been linked to elevated fear responses before.

The researchers themselves were very careful simply to discuss the results and didn’t make any value judgements on their claims, but the Slate article makes the point that it was widelydiscussed as if the study found a weakness in conservative voters.

These interpretations are interesting, because they immediately make a value judgement about whether the fear response is appropriate or not. As the Slate piece notes, another interpretation is that liberal participants were less emotionally responsive.

Most pointedly, the article also suggests a wider bias in the interpretation of studies on individual politics so differences linked to conservative views are cast in a negative light, and that this could be due to the overwhelming number of Democrats in science.

Unfortunately, the piece doesn’t do a good job of separating the scientific findings, the researchers’ interpretation and the subsequent commentaries (although no more so than other science articles) but the main thrust is relevant to the distinction between data and its meaning.

This is a pervasive problem in psychology and neuroscience and one researchers are very careful to avoid, at least in the scientific literature. That is, not to over-interpret the findings or the significance of a single study.

Individual studies cannot be interpreted without reference to other scientific work, not least because the methods are usually drawn from a base of other studies which have validated them. Individual studies also rarely provide evidence that any value-based interpretations are correct.

However, this also means that critiques that aim to counter the negative value judgements based on a dissection of the methods without reference to other studies are equally as invalid.

This was the case with a prior Slatearticle that had some valid points but was generally remarkably off key for this reason as it picked apart the details of the method without reference to the amount of evidence for their validity.

It’s a bit like saying “a neurologist says my friend has brain damage, but he used a Babinski sign test that involved stroking the bottom of his foot – but the foot is at the other end of the body!”.

Even seemingly implausible methods can be valid because science is full of counter-intuitive findings. The important thing is not how they seem on the surface, but what other scientific evidence supports them.

Political bias in the interpretation of studies on personal politics is widespread, so beware of any over-interpretation in either direction, and take anyone who uses a single study to make their point with a pinch of salt.

UPDATE:Wired Science has some good commentary on this post and notes I may have been too hasty (i.e. wrong!) in my judgement of the press coverage of the recent study, which was generally more careful than I had given it credit for.

Link to Slate article on bias in neuroscience interpretation.Link to text of recent Science study.Link to PubMed entry for same.